InCHIANTI is being performed in two sites: Greve in Chianti (Site 1; 11,709 inhabitants; 19.3% > 65 years; located in the middle of a rural area) and Bagno a Ripoli (Village of Antella, site 2, 4704 inhabitants; 20.3% > 65 years; located immediately adjacent to the urban area of Florence). To obtain two representative samples of the population, the same two stage sampling procedure was used in each of the two sites. For the baseline cohort, in August 1998, a random sample of 1270 persons aged 65 years or older was randomly selected from the population registry of the two sites. Another 29 subjects were randomly selected among those who were 90 years old or older, until at least 30 men and 30 women from this age group were included in the sample. Finally, men and women randomly sampled from the age strata 20-29, 30-39, 40-49, 50-59, and 60-64 years were sequentially invited to participate in the study, until at least 30 men and 30 women for each decade from 20 to 59, and 15 men and 15 women aged 60 to 64 had been enrolled. An overarching hypothesis of the study is that most persons with walking disabilities have limitations in one or more of six physiologic subsystems and that the clinical evaluation of these subsystems can be valuable in planning both treatment and preventive interventions. These subsystems include: 1) Bones and joints; 2) Muscles; 3) Central nervous system; 4) Peripheral nervous system; 5) Perceptual system; and 6) Energy production and delivery. In addition to the clinical assessments done during the examination a large library of biological measures have been accumulated through NIA funding and collaborations with outside investigators. The InChianti Study cohorts were assessed at baseline in 1998-2000, 3 years later, in 2001-2003, 6 years later, in 2004-2006, 9 years later, in 2007-2009, and just completed a fourth wave of follow-up, funded by the Tuscany Region Government, in 2013-2014 at both sites. In the fourth wave, approximately 687 interviews were conducted and 560 clinical examinations of participants. Follow-up examinations repeat most elements of the baseline evaluation.